air conditioner question - Diesel Forum

Greenie · 02-21-2008, 06:47 PM

Our roof top RV (duo-therm) runs cold at first but then seems to ice up- air coming out of the discharge vents appears to be blocked after the unit runs for a while. If left on it sounds like ice letting out in the unit and then the drip starts.
If we shut it off periodically it will keep flowing but not as cold as we'd like it to be.
Any ideas on what's going on?

Daisymay77 · 02-21-2008, 06:53 PM

I am a retired AC contractor, and after 30 some odd years in the business, I can tell you that the only reason your unit will ice up is either a restriction of airflow over the evaporater coil, or low refrigerent charge. Check to make sure your don't have a dirty filter in the return air, look at the evaporater coil when the air slows down it is probably at least partially blocked with ice. The drip you see is when that ice starts to melt. make sure the fan is running at full speed. If the airflow is not blocked and and the fan is running correctly,have the refrigerant charge checked.

Greenie · 02-21-2008, 08:46 PM

The fan speed was set on low, maybe that was the problem.
Many thanks!

**Mark Kovalsky** · 02-21-2008, 09:05 PM

My RV will freeze up the AC every time with the fan on low. It works fine with the fan on high.